The present invention relates in general to turning machines and in particular to a new and useful arrangement for power operated chucks for such turning machines.
Power operated chucks for turning machines which include radially adjustable master or clamping jaws, have tangentially extending wedge bars which are drivable and engaged with the clamping jaws for actuating the jaws.
A chuck of this kind has proved to be very satisfactory in practice and is known from U.S. Pat. No. 4,094,522 German (AS No. 25 56 227). In this design, the control member is provided with flat or curved wedge surfaces which extend in the direction of the wedge bars and are inclined in the direction of diplacement thereof and cooperate with opposite surfaces provided on the wedge bars. Even though that chuck comprises only few parts, and is thus not very susceptible to trouble and in inexpensive to manufacture, experience has shown, especially with numerically controlled machine tools, that at high speeds, the inwardly directed clamping force is reduce by the opposite centrifugal forces acting on the jaws, or, with an inside chucking, the forces add, because no compensation for the centrifugal forces is provided. It has further been found that with a direct engagement of the control member in wedge bars by means of radially projecting extensions formed thereon, the chucking capacity is affected. Therefore, in this chuck, the spindle passage area cannot be enlarged easily without unfavorably affecting the jaw guides or taking some other special measures.